Checking Fuel Tank and Tank Venting System For Leaks (Petrol/Gasoline Cars With Leak Diagnosis Pump/US Version)

16 00 100 - Checking fuel tank and tank venting system for leaks (petrol/gasoline cars with leak diagnosis pump / US version)





Special tools required:
- 13 3 010 13 3 010 Hose Clip
- 16 1 161 16 1 160 Seals
- 16 1 171 16 1 170 Tester with Test Adapter
- 16 1 174 16 1 170 Tester with Test Adapter





Necessary preliminary tasks:
- Remove rear right wheel arch trim Service and Repair





The following procedure is only applicable to cars with the leak diagnosis pump (US version).
Comply with the following conditions in order to obtain plausible test results:
- Content of fuel tank:
1. Maximum 90 %
2. Minimum 13 % (reserve telltale must not light up).
- Park the car in the workshop at least 2 hours before the test so that the fuel temperature is approximately that of the workshop temperature
(ideal fuel temperature approx. 10 ... 20 °C).





Clean housing of dust filter (1).
Slide special tool 16 1 161 16 1 160 Seals over vent openings of dust filter.

Important!
Slide special tool 16 1 161 16 1 160 Seals on dust filter (1) until openings are sealed.

Tighten down hose clip (2).





Remove fuel filler cap and connect special tool 16 1 174 16 1 170 Tester with Test Adapter to fuel filler neck.
Clamp special tool 16 1 174 16 1 170 Tester with Test Adapter on fuel filler neck with adjusting wheel (1).





Important!
Turn pressure regulator on special tool 16 1 171 16 1 170 Tester with Test Adapter counterclockwise up to stop.





Connect special tool 16 1 171 16 1 170 Tester with Test Adapter using compressed air line (1) to garage compressed air system (8 ... 10 bar).
Connect pressure sensor (2) from Diagnosis and Information System with a measuring range of 0 ... 25 bar.

Important!
Do not yet connect fast-release coupling (3) of special tool 16 1 171 16 1 170 Tester with Test Adapter.





1. Select "Measurement" function on Diagnosis and Information System (DIS).
2. Using pressure regulator on special tool 16 1 171 16 1 170 Tester with Test Adapter, increase pressure by 0.20 bar.
3. Connect special tool 16 1 174 16 1 170 Tester with Test Adapter to fast-release coupling of special tool 16 1 171 16 1 170 Tester with Test Adapter.
4. Wait until the value at the Diagnosis and Information System has levelled out.
5. Using pressure regulator on special tool 16 1 171 16 1 170 Tester with Test Adapter, reset gauge pressure in fuel tank to 0.20 bar.





Important!
Do not under any circumstances increase pressure by more than 0.30 bar as this would result in damage to the fuel tank and venting system.





Using special tool 13 3 010 13 3 010 Hose Clip, disconnect delivery line from special tool 16 1 171 16 1 170 Tester with Test Adapter to fuel filler neck.
Allow a rest period of approx. 20 sec.
Read off and note down starting pressure value.
Wait approx. 120 sec.
Read off final pressure value and compare with starting pressure value.





Measurement evaluation:
- Pressure drop up to 0.01 bar:
System OK
- Pressure drop over 0.02 bar:
System leaking beyond permitted levels
If the system is leaking, a leak test Conducting Leak Test on Fuel Tank and Tank Venting System must be carried out and the defective components replaced.